In my caffeine-induced delerium, I seemed to remember some notes from Matt Sergeant in the early days of DBD::SQLite to the effect that he did something different and sped things way up. I scanned his entire journal and found out that what he did was turn off auto-commit and just commit every thousands INSERTS or so. I'm making a note of this here so I can remember it and also in case it will help anyone else.
Apparently SQLite effectively does a commit on every statement when you have auto-commit on.
For the record, Monster energy drink compares horribly to Mountain Dew Amp, although it's a mere 16 cents more for twice as much. That said, both leave me with the unmistakeable feeling of having been ripped off.
Update: don't try to commit every 18,000 records, even if you're tempted by the fact that each of your data files contains about 18,000 records and you think you'll gain the security of being able to rollback when you interrupt in the middle of your data load. Committing every 50, 100, 500, or 1000 statements is good, depending on your circumstances.